Portable fans, such as box fans, are popular as a cost-efficient means for cooling or ventilating interior areas of commercial and residential buildings. Box fans are inexpensive, light, and portable, and can be easily repositioned to provide a desired interior air flow.
Filters have been applied to box fans as a means for removing air-borne contaminants from the air flow. A number of mounting configurations have been devised that secure a filter to a box fan. U.S. Design Pat. No. DES 377,390 discloses a filter mount that is incorporated within the body of a box fan. This configuration requires a specialized fan chassis, and therefore is not applicable to general-purpose box fans. U.S. Pat. No. 4,781,526 discloses a filter mount that is affixed to an exterior portion of a fan body. In this configuration, the filter bracket is permanently affixed to holes formed in the fan body using specialized mounting hardware, such as machine screws. U.S. Pat. No. 6,527,838 discloses a filter mount including a plurality of brackets that adhere to a side surface of the fan. The brackets are permanently affixed to the fan, and take the form of specialized hardware, which, when mounted to a particular fan body, cannot be re-used on another fan. In alternative embodiments disclosed in the U.S. Pat. No. 6,527,838, a filter bracket is applied to a fan body using hook and loop fasteners or screws about a periphery of the body of the fan. Again, such specialized attachment hardware is semi-permanent, can disfigure the fan body, and cannot be re-used on another fan.